Rinse the rice under cold water. Tip into a pan. Add 150ml boiling water and a pinch of salt. Cover. Bring to the boil. Turn the heat right down and simmer for 25 mins till the water is absorbed. Take off the heat. Set aside, lid on, for 5 mins to finish cooking the rice.
Peel and finely chop half the red onion. Pop it in a small bowl and cover with cold water. Set aside for 10 mins - this will help mellow the flavour of the onion.
While the rice cooks, scrub and peel the beetroot. Roughly chop it. Pop the chunks into a food processor (or coarsely grate onto a plate) and blitz to make ‘rice’. Tip into a large mixing bowl.
Pick thick stalks out of the watercress. Finely chop the leaves and thinner stalks (see tip below). Add them to the beetroot.
Pick the leaves off the basil, coriander and mint sprigs. Pile them up on your chopping board with the chives. Rest the tip of your knife on the board and, using rocking motions, finely chop all of the herbs. Add most of the herbs to the bowl. Drain the onion and add it to the bowl.
Zest the lemon and add most of that, too. Tip the rice into a sieve. Rinse under cold water. Shake dry. Add to the bowl.
Juice the lemon. Whisk it with 1 tbsp oil and salt and pepper to make a dressing. Add to the bowl and gently stir.
Peel the skin off the salmon. Flake it into chunks. Divide the salad between 2 bowls or plates. Top with the salmon. Sprinkle with the leftover herbs and lemon zest.